This invention relates to a spring support device for pipes, boilers or other structures exposed to heat. The spring support is of the type which exerts an essentially constant support force as the load is vertically shifted. The spring support has a load-carrying pull rod which is engaged by at least two identically structured and symmetrically arranged bell crank levers. The latter are articulated to the pull rod at the end of their generally radially extending arm. The load exerted on the pull rod is supported by a spring through the intermediary of the bell crank levers and a spring disc. The spring which is, in turn, held at its other end by a stationary support is constituted by at least one compression spring which is arranged essentially parallel to, or coaxial with, the pull rod. The bell crank levers are in engagement with the spring disc or similar component in a slidable manner, for example, by means of a roller carried by each bell crank lever.
A spring support of the above-noted type which essentially may be used for suspending a load therefrom or placing a load thereon, is disclosed in German Published Accepted Patent Application No. 1,291,581. The other, external ends of the bell crank levers are articulated to essentially vertically oriented tension bars which are attached to a pressure beam constituting a fixed support for the spring system. In such a structure, during vertical motion of the pull rod and thus, during the pivotal motion of the bell crank levers, the arm advantages vary between the outer end and the slidable support on the one hand, and the slidable support and the inner end, on the other hand, whereby a change in the reaction force of the spring system is compensated in a large measure. Spatial requirements are relatively large in the direction of the bell crank levers because of their required length and thus it is practically indispensable to arrange a plurality of compression springs side-by-side along this direction. Further, the above-outlined known structure delivers an approximately constant support force only over a relatively small setting range of the pull rod.
Further, in German Patent No. 1,203,065 there is disclosed a spring support which operates with three springs of identical dimension. One spring is oriented vertically, whereas the two other springs are disposed laterally swingably and, in the neutral position of the spring support, in which they are oriented horizontally, they do not exert any force. In all the other positions, the two lateral springs correct, by means of the force components oriented in the direction of the rod, the force of the vertical springs varying with the displacement of the rod. In this manner there is obtained a practically constant support force for the load so that in case of a heat expansion-caused vertical change of position, no additional transversal force or decreased support force will be exerted on the load. In this structure again, the lateral springs require in their direction, substantial structural space and further, the use of at least three springs is necessary.
Further, there are known spring supports in which the support force remains constant in a large measure and which, in essence, require the use of only a sole compression spring. The spring is oriented substantially horizontally adjacent the path of the pull rod and is connected therewith by means of a toggle joint which is so dimensioned that there is obtained a substantially constant support force throughout the permissible rod path. Such an asymmetrical construction, however, leads to a laterally projecting structure and it is necessary to design the spring, corresponding to the ratio of the arms of the toggle joint, stronger than it would otherwise be necessary for carrying the load. Further, the permissible rod path is significantly limited.